Back out "Revert D31299350: Back out "Revert D31005792: [NCCL] Init dummy NCCL comms in constructor"" (#66393)
Summary:
Pull Request resolved: https://github.com/pytorch/pytorch/pull/66393
Third try!
Fixes:
- test_nccl_timeout can be flaky because of 1s timeout, bump up the timeout to resolve the flakiness. But in general we should not have been relying on time.sleep for this test, filed https://github.com/pytorch/pytorch/issues/66354 to track that.
- ciflow/all did not actually run tests due to a bug causing multigpu tests to not be run. This has since been fixed.
ghstack-source-id: 140560113
Test Plan: CI
Reviewed By: mrshenli
Differential Revision: D31534735
fbshipit-source-id: 8b7e0f4fed3972b7a77cbcda28876c9eefb0c7e2
